codewars #34 Write Number in Expanded Form (6kyu)

#34 Write Number in Expanded Form

Write Number in Expanded Form

You will be given a number and you will need to return it as a string in Expanded Form. For example:

Kata.expandedForm(12); # Should return "10 + 2"

Kata.expandedForm(42); # Should return "40 + 2"

Kata.expandedForm(70304); # Should return "70000 + 300 + 4"

NOTE: All numbers will be whole numbers greater than 0.

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class Kata
{
    public static String expandedForm(int num){
    	List<String> result = new ArrayList<String>();
    	while(num!=0){
        	int length = String.valueOf(num).length();
        	int cutoff  = new BigDecimal(num).setScale(-length+1, BigDecimal.ROUND_DOWN).intValue();
        	num -= cutoff;
        	result.add(String.valueOf(cutoff));
        }
    	return result.stream().collect(Collectors.joining(" + "));
    }
}